Re: [dpdk-dev] [RFC V1] examples/l3fwd-power: fix memory leak for rte_pci_device

[Thomas Monjalon <thomas@monjalon.net>]

08/09/2021 04:01, Huisong Li:
> 在 2021/9/7 16:53, Thomas Monjalon 写道:
> > 07/09/2021 05:41, Huisong Li:
> >> Calling rte_eth_dev_close() will release resources of eth device and close
> >> it. But rte_pci_device struct isn't released when app exit, which will lead
> >> to memory leak.
> > That's a PMD issue.
> > When the last port of a PCI device is closed, the device should be freed.
> 
> Why is this a PMD problem? I don't understand.

In the PMD close function, freeing of PCI device must be managed,
so the app doesn't have to bother.

> As far as I know, most apps or examples in the DPDK project have only 
> one port for a pci device.

The number of ports per PCI device is driver-specific.

> When the port is closed, the rte_pci_device should be freed. But none of 
> the apps seem to do this.

That's because from the app point of view, only ports should be managed.
The hardware device is managed by the PMD.
Only drivers (PMDs) have to do the relation between class ports
and hardware devices.

> >> +		/* Retrieve device address in eth device before closing it. */
> >> +		eth_dev = &rte_eth_devices[portid];
> > You should not access this array, considered internal.
> 
> We have to save the address of rte_device to free rte_pci_device before 
> closing eth device.
> 
> Because the the device address in rte_eth_dev struct will be set to a 
> NULL after closing eth device.
> 
> It's also handled in OVS in this way.

No you don't have to call rte_dev_remove at all from an app.

> >> +		rte_dev = eth_dev->device;
> >>   		rte_eth_dev_close(portid);
> >> +		ret = rte_dev_remove(rte_dev);